Aloe vera, a tropical or subtropical plant of the genus Aloe, has lance-shaped leaves with jagged edges and sharp points. The leaves contain a viscous but essentially clear gel given structural rigidity by hair-like connected fibers that run through it. Freshly excised from the plant and applied in vitro, this gel has been used medicinally for centuries by those living where the plant normally grows to relieve the pain of plant and animal stings, such as jelly fish stings.
The clear gel of aloe vera is to be distinguished from the thick, mucilaginous yellow juice that occurs about the base of the plant leaves and adjacent to the rind of the leaf. This juice, known as aloin, has been used for many years as an ingredient in many carthartics and purges.
The therapeutic qualities of the clear gel of the aloe vera depends on the freshness of the gel. For example, the pain of a jelly fish sting may be stopped, not to reoccur by applying the clear gel from a leaf that has just been cut, but if the gel has been exposed to air and light for about one and one-half hours, these powers are partially lost. Gel that has been removed from a freshly cut leaf for as little as three hours is only about 40% as effective as fresh gel. Yet, fever blisters have been treated successfully with gel that has been extracted for several weeks, though not with gel as old as three months. Apparently, the varying efficacy of the fresh gel for different medicinal purposes reflects the fact that the gel is a complex mixture of substances whose stability on exposure to air and light differ from one batch to another. In addition to loss of therapeutic efficacy on aging, decomposition products occur after a short time that may make the natural gel even less useful than it might be.
Several processes have been provided to prolong the effective life of the aloe vera extract. These attempts include U.S. Pat. No. 3,878,179 which discloses a process for the extraction and stabilization of the aloe vera gel by treating it under ultra violet radiation at ambient temperature to produce a biologically sterile and chemically stable extract. Other processes for stabilizing aloe vera gel are disclosed in U.S. Pat. Nos. 3,892,853 and 4,178,372.
U.S. Pat. No. 3,892,853 discloses a method to stabilize gel by adding catalytic portions of a nontoxic oxidant and heating the gel from 35.degree. C. to about 80.degree. C., the processed gel is then buffered to maintain a pH in the range of 4 to 8. Other ingredients may also be added to achieve desired or cosmetic purposes.
U.S. Pat. No. 4,178,372 discloses a process for stabilizing aloe vera gel utilizing a non-toxic oxidant, heating the gel from about 35.degree. C. to about 80.degree. C., after which ascorbic acid and a buffer is added to produce a hypoallergenic stabilized aloe vera gel.
The popularity of aloe vera products has dramatically increased, expanding the market area for the gels far beyond the regions where aloe vera may be grown. Thus, as the distance of the market area has increased from the area of production, a need has arisen to provide an aloe vera gel of improved stability. While earlier processes have increased the shelf life of the product, improvement has been needed. The present invention provides a method whereby the shelf life of aloe vera gel extract can be significantly increased.